Electrical musical instrument



J. M. HANERT 2,687,665 ELECTRICAL MUSICAL INSTRUMENT Filed Nov. 2, 1951 #8 (g V :2 2* V zr i mm'ro OSCILLATOR 4! 42 OSCILLATOR APPARATUS 1044:

r 1' .5 K F '1' 5 K Aug. 31, 1954 c 42 OSCILLATOR 1* '1- s K Z531 M T Patented Aug. 31, 1954 2,687,665

uurrso stares PATENT OFFICE 2,68 7, 665 ELECTRICAL MUSICAL INS TR-UMENT John M. Hancrt, Des Plaines, IIL, assignor to Hammond Organ Company, a corporation of Delaware Application November 2, 1951, Serial No. 254,573 5 Claims. (01. 8'=1.01)

My invention relates generally to electrical organ is said to be straight. It then becomes musical instrument and more particularly to ima vastly superior instrument in WhlCh one key proved electronic organs in which the tone sigdoes not rob anything from the tones of any nals are generated by oscillators which are norother key of the instrument. 1

mally not oscillating. 5 Other electric organs have been made in which signal output circuit of the oscillator is perms ance in such manner that when a tone signal nently coupled to the output system of the instrusource was required to supply the unison coinment. Thus, whenever a signal from an oscillo ponent for one note and at the same time supply lator is required, a key operated switch completes an octave coupler component for another note, a circuit to impress an operating potential upon the output of the generator was held at a relaone of the electrodes of the vacuum tube, usually tively constant value and additive results were through a resistance-capacitance delay network obtained across a signal impedance having a so as to cause the osclllator to commence oscill;

one of the electrodes of the vacuum tube is ada there is difiiculty in avoiding transients due to depression of a key. The vacuum tube and its rather elaborate precautions must be taken even associated components will therefore have an if variable impedance keying elements are emextended useful life. 2.5 ployed.

However, this type of electronic organ has a It is therefore a primary object of the invendisadvantage in common with the unified pipe tion to provide an improved electronic musical organ in that if octave couplers are used, deinstrument in which electronic oscillators are pression of two keys an octave apart will not proemployed as the tone s gnal generators, n which duce additive results as would be expected after 3 signals of different tone quality may be derived,

caring each of the tones sound sepa ately and in which octave couplers are employed withsuitable loudness and quality. Under these con- 35 characteristics of a direct current keyed oscilditions, the movements of the tenor and alto later having a suitable time delay mesh for convoices in contrapuntal music would be clear and trolling attack and decay.

good plan, of course, would he to provide another 4. graph in which signals of different tone qualities pected tone is heard. If one plays the lower key signals are generated by oscillators and since sounds week because it has no unison component the possibility of failure of the instrument to play but merely plays its octave coupler component. 50 a note called for by the depression of a key is Unification tends to spoil the ensemble of the increased if all the oscillators are operating durorgan because the inner voices of contrapuntal ing the time that the instrument is being used. music cannot be clearly distinguished. If, on the In the playing of most selections the musician other hand, all the voices add in proper pro- V usually will not have more than six keys deportions regardless of the interval played, the pressed at one time. Thus, if the instrument contains sixty oscillators, only approximately onetenth of the oscillators will be operating at any one time and the useful life of the tubes will therefore be extended considerably. Of course factors other than the application of plate voltage to a tube which may causes it to age, but the life, of most vacuum tubes may be gaged fairly well by the length of time plate current is flowing in the plate circuit tube. Furthermore, the cost of an instrument of this type is determined largely by the number of oscillators employed. In the instrument presently to be described each oscillator serves to supply the tone signals for two adjacent semitone intervals because it is infrequent that adjacent semitones would be played in most musical selections. Thus one oscillator may very well serve to supply the signals for two adjacent semitones, thereby reducing by substantially one-half the number of tubes and oscillator components required.

It is therefore a further object of my invention to provide an improved electrical musical instrument in which the number of oscillators required is reduced by substantially one-half, in which plate current is supplied to the oscillator tubes only while their output is being used, and by which true octave coupler effects may be obtained.

Other objects will appear from the following description, reference being had to the accompanying drawings in which:

Figure l is a schematic wiring form of oscillator ment; and

Figure 2 is a schematic wiring and block diagram of a representative portion of the instrument.

The oscillator shown in Fig. 1 is of the Hartley type, modified as to specific circuit arrangement and values of components, and is more fully described and claimed in my copending application Serial No. 224,276, filed May 3, 1951, now abandoned. The oscillator comprises a vacuum triode having a cathode l I, control grid l2, and anode or plate l3. The cathode is connected to a tap on an inductance Ll d which has a tuning capacitor CNS in parallel therewith, one terminal of the LIA and C16 mesh being connected to ground while the other terminal of this mesh is connected to a terminal F and connected to grid l2 through a capacitor CIS. The cathode is also connected to a terminal T through a tuning capacitor C20. The grid I2 is connected to a source of vibrato pulses, indicated as a terminal V, through a resistor R22. Plate current is supplied through a keying terminal K which, as will appear hereinafter, is adapted to be connected by a key-operated switch to a 3+ terminal of the power supply.

Terminal K is connected to the plate 13 through a mesh comprising a resistor R24 having in parallel therewith a second lower-value resistor R26 which is in series with a capacitor C28. The mesh R24-R26--C28 is connected to the plate 13 through an additional resistor R30 and the plate is connected to ground through a resistor Rail and an attack and decay capacitor C32. The signal appearing upon the plate 3 passes through a blocking capacitor C34 and is impressed across a coupling resistor R36, one end of which is grounded nected to C35 as well as to a terminal S.

It will be understood that upon applying plate potential to the terminal K an initial surge of plate current will pass through capacitor C28 and relatively low value resistors R26 and R39 and diagram of a suitable for use in an instruand the other end of which is conin addition the capacitor C32 will. be rapidly charged. Thereafter the plate current is continuously supplied through R2 3 and RM and capacitor C32 will become charged to its normal operating potential. Thus'even though the voltage on the control grid i2 is negative, due to the fact that the plate current happens to start being supplied at the instant that the vibrato voltage is in the negative phase of its cycle, the oscillator will start promptly at the correct frequency. However, the rate of attack will be slowed by the time constants of the mesh R2 l-C32-R3tl, so that a smooth attack will result. Similarly, upon disconnection of the source of plate poten tial from the terminal K, the capacitor C32 will continue to supply plate current at a diminishing potential thus assuring a smooth decay of the tone.

The signal appearing between the terminal F and ground will be substantially a sine wave, corresponding to a tone of a flute-like character, whereas the signal appearing across R33 at the terminal S will be highly complex, representative of a tone quality of the string family.

In Fig. 2 there are illustrated as blocks til, ll, and 62 three oscillators, each of which is of the circuitry shown in Fig. 1, except for minor changes in the values of some of the circuit components. The oscillator as is adapted to supply electrical tone signals of the notes C! and Cit, it being understood that the capacitor Cfiil is of such value that when the terminal T is connected to ground the pitch of the oscillator will be reduced by a semitone interval. Oscillator M is adapted to provide tone signals of the pitch C2 and C21; while oscillator 42 is adapted to supply tone signals of the pitch C3 and can Each of the oscillators is provided with a tuning switch it which, upon depression of the lower of the two playing keys 45 with which the oscillator is associated, is adapted to connect the terminal T of its oscillator to a grounded bus bar it. In addition, each of the keys operates switches 58, t9, and st. Switches A4, Q8, and 5% are arranged so as to close prior to the switch it whenever a key is depressed, and to open last upon release of the key. Each of the switches is adapted to connect the F terminals of its associated oscillator to a bus bar 52 through a decoupling impedance Z53, to complete a circuit for conducting the flute signal to the output system of the instrument. The impedances Z53 are illustrated as resistors, but in some instances might be capacitors, or possibly inductance elements. If capacitors, they could be used also as keying switches in the manner shown in Curtis Reissue Patent No. 21,554. Switches 49 are adapted to make connections between the terminal S of the oscillator and a bus bar 55 through a decoupling impedance Z53, to complete circuits for the conduction of the string tone signal to the output system of the instrument. Until one of the switches t8 is closed the oscillator is not operating, so that when this last-to-close switch is closed plate current is supplied from the 13+ bus bar 55 to the terminal K of the oscillator. As previously indicated, the oscillator will-then commence oscillating with a smooth attack and will transmit flute signals to the bus bar 52 and string type signals to the bus bar 53.

In addition to operating the switches previously mentioned, the key Cl is illustrated as arranged to operate a switch and keys Cl and Cl# are each adapted to operate similar groups pitch corresponding to nects the tuning switch 50 to the T terminal It will be understood that some of the princiof oscillator 41. The switches 61, which make ples of the invention may be embodied in instruconnections to a 13+ bus bar 69, are closed after ments in which an oscillator is employed for each the other switches 60, 62, and 63 have been closed note, in which event the tuning capacitors C nects the terminal S of oscillator 4| to a bus Depending upon the effects desired one or both bar 70 through a decoupling impedanc Z53, and of the tablets 64, 90 may be op rated to close similarly closure of either of the switches $3 coneir associated switches whereupon depress on nects the F terminal of oscillator 41 to a bus bar of any of the keys, such for example as the key C2, 12 through another decoupling impedance Z53. 20 will result in tuning the oscillators 40, 4!, and

Thus if the 4 ft. coupler tablet s4 is operated 42 to the pitches of the notes Cl, 02, and. C3 and one of the keys, for example Cl, depressed, respectively; condition the circuits to supply flute closure of its switches 44 and 50 will first tune quality, string qu ty, 0 bo typ of signals o will condition circuits for supplying the string sigfinally, render each of the three oscillators opernals from oscillators 40 and 4! to the output. ative by supplying plate current thereto. Closure of switches 59 and 63 will condition the It will be understood that in Fig. 2 only a repcircuits for transmission of the flute tone signals rcsent ive p ion f th in r m n i illusto the output. Thereafter, closure of the switches trated and that-each octave of keys, except the 48 and BI will supply plate current to oscillators keys for the lowermost octave, will be provided and 4! respectively, causing these oscillators with switches 80 to 83. Each except the u perstring quality signals to the output system of to S3, and all switches will be connected in the instrument. 35 the manner illustrated and described.

The key C3, in addition to operating its switches The instrument is played in the customary 44, 48, 49, and 50, operates a tuning switch 33 manner of an organ, operating the various conand each of the keys C3 and 034% operates one r l and pr ing he p a i k y 5- Full A 16 ft. coupler tablet 90 is adapted t te 40 be obtained. If the instrument has but one manoperated, I04 and H0 for each register Since the tuning Switch 80 co-operates with a grounded bus bar circuits and the circuits connecting the oscilla- 94, switches 8| are adapted to complete a cir- 1301: puts o t put system are Operated Q ts to a flute signal bus bar 9?. Thus when- While I have shown and described particular ever the key C3 is depressed appropriate signals m fl Of my invention, it W l be pp from its associated oscillator 42 and additional 1;0 th Se Skilled i t art that numerous modi- 48 and a! are l d the more fundamental principles of the invention.

Bus bars 54, 10, and 96 are respectively con- I therefore desire, by the following claims, to innected t switches m 32, and 33 which are clude within the scope of my invention all such operated by a suitable tablet I0 which is n 6() similar and modified forms of the apparatus dismally m sm t grgund th bus bars, t closed, by which substantially the results of the when operated, connects these bus bars to a siginvention may be Obtained y substantially th nal collector conductor H35. Same equivalent means- In a similar manner the bus bars 52, 12, and Iclaim: 91 are respectively connected to switches I05, I01, n an electrical mu al strum nt havin and I98, these switches being normally grounded, an Output System t e combination of an elecbut being arranged to connect these bus bars to trical musical t signal gen r having input the collector conductor we when a tablet us is a Output terminals, sa generator up n a nected to one end of an impedance element ZI I2, sting Potential is mpr s d across its input terthe value of which is low relative to the values minals, a playing y, tWO wit hes Operated seof the decoupling impedances Z53, to obtain addiquehtially y, a Circuit iheludihg e i sttive results when an oscillator has its output coup t d s ch o up e t u p m na s pled to an amplifier H4 through more than one of the generator to the output system, and a sec- Of the mp n Th oth r n of im- 0nd circuit including the second-operated switch musical tone signal generators each having input and output terminals and supplying a signal to its output terminals only when an operating potential is impressed. across it input terminals, a playing key, two groups of switches operated sequentially thereby, circuits each including one of the first-operated group of switches and a relatively high value impedance to couple the output terminals of at least two octavely related generators to the output system, and additional circuits each including one of the second-operated group of switches for connecting the input terminals of said octavely related generators to a source of operating potential.

3. In an electrical musical instrument having an output system with an input circuit of relatively low impedance, the combination of two octavely related electrical tone signal generators, each generator having output and input terminals and operable to supply a tone signal to its output terminals when an operating potential is impressed across its input terminals, first and second playing keys, at least four switches operable by each key and arranged so that two of the switches will be operated before the other two are operated, parallel circuits each including an impedance of relatively high value and one of the early-operated switches for coupling the output terminals of the generators respectively to the output system, and additional circuits each including one of the late-operated switches for impressing operating potentials across the input terminals of the generators respectively.

4. In an electrical musical instrument having an output system, the combination of a first and a second electronic oscillator, a first key, a second key spaced an octave from the first key, decoupling impedances and switch'means operable by the first key to couple the outputs of the first and second oscillators to the output system, decoupling impedances and switch means operable by the second key to couple the output or the second oscillator to the output system, two switches in parallel operable by the first and second keys respectively to supply energizing current to the oscillators, said last named switches being operated on the downstrokes of the keys after all of the other switch means have been operated.

5. In an electrical musical instrument having an output system, the combination of a first electronic oscillator, a second electronic oscillator having a tuning circuit including an impedance to change its pitch, a first key, a second key spaced an octave from the first key, decoupling impedances and switch means operable by the first key to couple the outputs of the first and second oscillators to the output system, decoupling impedances and switch means operable by the second key to couple the output of the second oscillator to the output system, a switch operable by the first key effectively in the tuning circuit of the second oscillator to change the pitch of the latter, two switches in parallel operable by the first and second keys respectively to supply energizing currents to the oscillators, said. last named switches being operated on the downstrokes of the keys after all of the other switch means have been operated.

References Gitecl in the file of this patent UNITED STATES PATENTS Number Name Date 2,403,090 Larsen July 2, 1946 2,432,152 l-lanert et a1 Dec. 9, 1947 2,505,182 Haller et a1 Apr. 25, 1950 

